1. Field of the Invention
This invention relates to the field of circulation systems for ponds, lakes and other bodies of water and more particularly to the field of such circulation systems for relatively large and deep bodies of water that require fairly high flow rates to be most effective and systems for smaller bodies such as municipal wastewater ponds that are designed primarily for treating domestic and industrial wastes and have special requirements to be effective.
2. Discussion of the Background
In regard to larger and deeper bodies of water that require high flow rates to be most effective, the fundamental goal of such systems is to create a nearly laminar surface flow out to the edges of the pond while uplifting water from the bottom depths of the pond. In doing so, the oxygen depleted water from the bottom depths is exposed to and absorbs oxygen from the atmosphere while undesirable gases such as hydrogen sulfide are passed off into the atmosphere. Additionally, an overall circulation pattern is generated in the pond that mixes the reaerated water throughout the entire pond. Such mixing in turn accelerates the biological and solar processes that clean up the water. The resulting cleansing is particularly desirable as it relates to controlling or removing weed growth, algae bloom, sludge buildup, fish kills, odors, high amounts of nitrogen and phosphorus, acidity, suspended solids, and other conditions.
Power availability to run the pump or impeller of the circulation system and seasonal weather conditions (e.g., surface ice) present great design challenges for optimum performance. Remote ponds or other bodies of water can be a particular challenge as the only available power source may be solar energy. Yet, the impeller of the system preferably will be able to lift and induce the flow of relatively large volumes of water from relatively large depths, as for example 30 to 50 or more feet, Further, the upflow or lifting must be done in a manner that spreads the water gently and evenly across the surface of the pond in a nearly laminar flow pattern. Otherwise, the overall flow and mixing of the uplifted water will not reach the edges of the pond and will simply be concentrated in the immediate area of the impeller leaving the outer reaches of the pond stagnant and untreated.
In a well designed system as indicated above, the surface of the pond would be continually renewed with water drawn up from the bottom depths while maintaining a laminar surface flow out to the edges of the pond. The surface water will then absorb oxygen from the atmosphere while undesirable gases such as hydrogen sulfide pass out of the water into the atmosphere. Among other beneficial actions, such surface reaeration and subsequent mixing and diffusion of the aerated water throughout the depths of the pond will increase desirable aerobic activity. It will also reduce suspended and dissolved solids in the water increasing pond clarity and aiding sunlight penetration and heat transfer for further cleaning.
In circulation systems for smaller bodies of water such as municipal wastewater ponds for treating domestic and industrial wastes, the high flow circulation pattern throughout the entire body of water discussed above is not always effective to process the wastes and in some cases can be counterproductive. One problem in such smaller ponds (e.g., 5 to 15 feet deep) is that the domestic and commercial wastes are usually much stronger and more concentrated. Also, such municipal wastewater ponds rely on more complicated mechanisms including biological and chemical ones for treating and processing the waste. These mechanisms involve the establishment of an upper, aerobic zone and a lower, anaerobic zone. Each zone is essential for the proper and overall treatment and processing of the various and different waste materials and each zone has its own biological and chemical needs that are often the opposite of the other and often detrimental to the other. Consequently, any thorough and overall mixing of the entire pond as in the earlier high flow systems for larger bodies of water will normally destroy the two zones and the effectiveness of the wastewater treatment pond.
With these and other considerations in mind, the water circulation systems of the present invention were developed.